Sonographic diagnosis of intrauterine growth restriction (IUGR) by fetal transverse cerebellar diameter (TCD)/abdominal circumference (AC) ratio.

OBJECTIVE

To evaluate the validity of TCD/AC ratio in predicting IUGR.

STUDY DESIGN

Prospective descriptive analysis.

SETTING

Maharaj Nakorn Chiang Mai Hospital, Chiang Mai University.

SUBJECTS

Women meeting the inclusion criteria consisting of: (1) singleton pregnancies after 28 weeks of gestation; (2) known accurate gestational age; and (3) clinically suspected IUGR.

METHODS

The patients were sonographically examined for TCD/AC ratio. The best cut-off value of TCD/AC ratio in predicting IUGR was determined by a receiver operating characteristic (ROC) curve. The fetus with a TCD/AC ratio greater than the cut-off value would be antenatally diagnosed as IUGR for every gestational week. Standard definition of IUGR was a low birthweight, less than the 10th percentile.

RESULTS

One hundred and sixty-seven pregnancies with suspected IUGR were analyzed. The prevalence of IUGR among the study group was 51.5%. The best cut-off value of the TCD/AC ratio for predicting IUGR was 15.4%, giving the sensitivity, specificity, positive predictive value and negative predictive value of 73.26%, 80.25%, 79.75%, and 73.86%, respectively.

CONCLUSION

The sonographic fetal TCD/AC ratio as a gestational age-independent method can be helpful in antenatal diagnosis of IUGR, especially in pregnancy with uncertain gestational age.